1. Origin of the Invention
The invention described herein was made in the performance of work under a NASA contract, and is subject to the provisions of Public Law 96-517 (35 USC 202) in which the Contractor has elected to retain title.
2. Technical Field
The present invention relates to traveling wave pumps, and in particular to traveling wave pumps employing electroactive actuators to excite flexural traveling waves in a pump core. The induced traveling waves form multiple sealed chambers in the pump core which transport gases or liquids from the pump inlet to the pump outlet.
3. Background Art
Conventional pumps use numerous physically moving parts that are subject to wear, material fatigue and fracture, or jamming. These conditions are often worsened by a mismatch in the thermal expansion characteristics of the various moving parts when the pump is subjected to temperature extremes. As a result, the moving parts of conventional pumps commonly fail leading to leakage and/or disablement of the pump. Thus, the long-term reliability of conventional pumps is a major concern. Additionally, conventional pumps are difficult to miniaturize because of the complexity of the various parts and their interaction.
There is an increasing need for miniaturized pumps which are capable of providing long-term reliability over a wide range of temperatures. For example, the current trend to reduce the size of a spacecraft to meet mission requirements has fueled a need for miniaturized, low mass pump mechanisms with long-term reliability and the capability of operating at cryogenic temperatures. In addition, it is desirable for these pump mechanisms to be less expensive than conventional pumps and capable of lower power consumption. Miniature pumps are used for a wide variety of applications on a spacecraft including the controlled supply of liquid and gas, thermal management, cooling systems and vacuum control devices. One example of a vacuum pump application is in a spacecraft used for planet surface sampling missions where soil, rocks, and other geological materials are collected. The samples are either analyzed remotely or returned to earth. For instance, some remote analysis instruments, such as mass-spectrometers, require the forming of a vacuum in a chamber in which collected samples are placed for analysis. Similarly, samples that are to be stored and returned to earth must often be preserved in a vacuum or an inert atmosphere which would be created by a pump mechanism.
A need for reliable, miniaturized pumps is also recognized by the medical community for many instrument applications. One example is the injection of fluids into the body of a patient at controlled times and dosages.
Thus, it is an object of the present invention to provide a pump device without moving parts to improve operating reliability and to facilitate the miniaturization of the mechanism.
It is another object of the invention to provide a pump whose performance is maintained at low temperatures.
Further, it is an object of the invention to provide a pump having a small number of components that are light weight, inexpensive and have minimal power consumption requirements.